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Part 3
Entries
Entry 9: April 10, 2012
In my UNIX class i learned how to better search through files and use the head(1) and sed(1) utility to take text out of the file i did not want. sed 's/pattern/replacement/g' = pattern searching for and then replace pattern searching for with this replacement and g means globally.head -25 file.txt = -n for number of lines you want to print of the file you choose which could then be piped to sed a stream editor to remove unwanted text. a basic line may look like this
head -25 file.txt | sed -e 's/[a-z]*5/:/g' print first 25 lines of file.txt and then search for text that start with a to z and end in 5 and once found replace that with colon globally in the file.
Entry 10: April 13, 2012
C++ class
A program can be split up into multiple files making it easier to edit and understand, especially in the case of large programs but also allows the individual parts to be compiled independently.
*when compiling a large program with multiple header file remember to add this line in the header file so you do not include the same header file twice in your program.
#ifndef _HEADERFILENAME_H #define _HEADERFILENAME_H
#endif
Entry 11: April 14, 2012
g++ -o prog file1.o file2.o file3.o compile c++ code into one executable named prog with the object files: file1 file2 file3. then you can now run ./prog on the command line because it is now an executable file.
To produce only .o files from source files without doing any linking invoke -c option
Entry 12: April 19,2012
some html i did in unix class that diplayes an image of myself and some general info
<html> <title> RM Lab46 Homepage</title> <body> <center>Unix Homepage by Robert Matsch</center> <img src="player.jpg" height="42" width="42" /> <strong>Who am I :</strong> <p>My name is Robert matsch, I am currently a student at corning community college. Upon completion of my Computer Information Science degreein in may 2012 i am attending RIT for the fall of 2012. I am majoring in software engineering and planning to live in california once i graduate to work with my uncle and be part owner in a private consulting company.I enjoy listening to music, being active, riding my motorcycle and best of all spending time with friends and family. </p> <hr> <br> Top 6 movies: <ol> <li>Step Brothers</li> <li>Hangover 1 and 2 </li> <li>Finding Nemo</li> <li>Bad Boys II</li> <li>Talladega Nights</li> <li>k-pax</li> </ol> <p> </p> <br> who is I ? </body> </html>
<html> <title> RM Lab46 Homepage</title> <body> <center>Unix Homepage by Robert Matsch</center> <img src=“player.jpg” height=“42” width=“42” />
<strong>Who am I :</strong> <p>My name is Robert matsch, I am currently a student at corning community college. Upon completion of my Computer Information Science degreein in may 2012 i am attending RIT for the fall of 2012. I am majoring in software engineering and planning to live in california once i graduate to work with my uncle and be part owner in a private consulting company.I enjoy listening to music, being active, riding my motorcycle and best of all spending time with friends and family. </p> <hr> <br> Top 6 movies: <ol> <li>Step Brothers</li> <li>Hangover 1 and 2 </li> <li>Finding Nemo</li> <li>Bad Boys II</li> <li>Talladega Nights</li> <li>k-pax</li> </ol> <p>
</p> <br> who is I ? </body> </html>
Entry 12: April Day, 2012
This is a sample format for a dated entry. Please substitute the actual date for “Month Day, Year”, and duplicate the level 4 heading to make additional entries.
As an aid, feel free to use the following questions to help you generate content for your entries:
- What action or concept of significance, as related to the course, did you experience on this date?
- Why was this significant?
- What concepts are you dealing with that may not make perfect sense?
- What challenges are you facing with respect to the course?
Remember that 4 is just the minimum number of entries. Feel free to have more.
cprog Keywords
• logic and operators (and, or, not, xor) • Scope (Block, Local, Global, File) • Type Casting • Structures (Declaration, Accessing Elements, Pointers to) • Type Casting Operators, Const-Volatility Specifiers (const, volatile) [C++] • Overloading (Functions, Operators) [C++] • Exception Handing (throw, try, catch) [C++] • Templates, STL (Standard Template Library) [C++]
Logic operators
Definition
logic operators are a logical operation on one or more logic inputs that produces a single logic output
Demonstration
a b | and or xor nor xnor nand notb nota F T | F T T F F T F T T T | T T F F T F F F F F | T F F T T T T T T F | F T T F F T T F
Type casting
Definition
Converting one type of data into another type of data.
Demonstration
short a=2000; int b; b = (int) a; b = int (a); or short a=2000; int b; b=a;
Templates
Definition
Templates in C++ template are classes to provide common programming data structures and functions. STL- standard template library is a library of templates
Demonstration
#include<iostream>
using namespace std;
template <class T>
void myfunc (T val1, T val2, T val3)
{
T result;
result = val1 + val2 + val3;
cout << "First value is: " << val1 << endl;
cout << "Second value is: " << val2 << endl;
cout << "Third value is: " << val3 << endl;
cout << "The sum of all three are: " << result << endl;
cout << "The average of all three are: " << (T)(result/3) << endl;
}
int main()
{
// some c code here
return 0;
}
Overloading Functions, Operators
Definition
You can redefine a function of most built-in operators in C++ by overloading globally or on a class. key point * Overloaded operators are implemented as functions and can be “member functions or global functions”.
You can also overload a function name by declaring more than one function with the that name in the same scope. when the program is being run and the function is call the program matches parameters up to select the right function.
Demonstration
Operator overloading
#include <iostream> using namespace std; class complx { double real, imag; public: complx( double real = 0., double imag = 0.); // constructor complx operator+(const complx&) const; // operator+() }; // define constructor complx::complx( double r, double i ) { real = r; imag = i; } // define overloaded + (plus) operator complx complx::operator+ (const complx& c) const { complx result; result.real = (this->real + c.real); result.imag = (this->imag + c.imag); return result; } int main() { complx x(4,4); complx y(6,6); complx z = x + y; // calls complx::operator+()
and now function overloading
#include <iostream>
using namespace std;
void print(int i) {
cout << " Here is int " << i << endl;
}
void print(double f) {
cout << " Here is float " << f << endl;
}
void print(char* c) {
cout << " Here is char* " << c << endl;
}
int main() {
print(10);
print(10.10);
print("ten");
and now the output from this function over loading
lab46:~$ ./funoverl Here is int 10 Here is float 10.1 Here is char* ten
Exception Handing (throw, try, catch) [C++]
Definition
key words that can “catch exceptions” by placing a portion of code under exception inspection and enclosing that portion of code in a “try block”. it works When an exception circumstance comes about within that block, the exception is then thrown which transfers the control to the exception handler. If no exception is thrown the code continues normally.
Demonstration
#include <iostream> using namespace std; int main () { try { throw 20; } catch (int e) { cout << "An exception occurred. Exception Nr. " << e << endl; } return 0; }
Scope (Block, Local, Global, File)
Definition
block: C++ names can only be used in parts of a program called the “scope” of the name. unless otherwise acres from a member of that class scope. this is very important in C++ because scope determines when variables local to the scope are initialized.
Local scope:A name declared within a block is accessible only within that block and blocks enclosed by it and only after the point of declaration.
File scope: Any name declared outside all blocks or classes has file scope also known as namespace scope.
global scope: is names with file scope that are not declare objects are global names.
Demonstration
local scope
{
int i;
}
Notice the declaration of i is in a block enclosed by curly braces so i has local scope and is never accessible because there is no code accesses before the closing curly brace.
class area()
{
int x;
int y;
};
x and y can be used to access the class area through “.”or “→”
Type Casting Operators, Const-Volatility Specifiers (const, volatile) [C++]
Definition
constant : makes that the type is constant but also the object shall not be modified. In doing so it may you may recieve undesired/undefined results such as compile time error compile-time error.
volatile: makes the type volatile and the object then be modified so that the compiler doesn't yell at you.
Demonstration
const int five = 5;
const double pi = 3.141593;
const objects may not be changed below is an example: <Code>
#include <stdio.h> #include <stdlib.h> int main() {
int result=0;
const int five = 5;
const double pi = 3.141593;
pi = 3.2;
five = 6;
result=five+pi;
return(0); } </code> compile msg below
lab46:~$ gcc -o const const.c const.c: In function 'main': const.c:9: error: assignment of read-only variable 'pi' const.c:10: error: assignment of read-only variable 'five'
Structures (Declaration, Accessing Elements, Pointers to)
Definition
Declaring : a structure it is in the form of a block of data which can contain different data types depending on means of a structure declaration.
Accessing elements: structure accessing is done by specify both the structure name (name of the variable) and the member name when accessing information stored in a structure.
Point:you can point to structs by deference them below is example
struct tag *st_per;
and we point it to our example structure with:
st_per = &my_struct;
Demonstration
struct person{ char *name;//or --char name[20]; unsigned char age; short int weight; float gpa; }; //struct differ from union bec struct allocate memory for each and dont share $ typedef struct person P; P p1,p2,p3,p4,p5; struct person p1; struct person p2; struct person p3,p4,p5; Accessing Members of a Structure p1.age = 29; point to : struct person *st_per; st_per = &my_struct; (*st_per).age = 63;
cprog Objective
cprog Objective
The course objective is to be able to successfully develop C code of a desired program. The program should work and any problems that come about can be figure out and finally manage the code with C++ and abstract details away for security and neatness.
Method
Develop a program that will allow a simpler way of doing something from creating a program of your choice. Have what you wish to be able to do and then program with the requirements chosen. produce a finished result
Measurement
I have develop a program that i thought was going to be easy and turned out my requirement i want i did not achieve so i changed them a little. the program accepts string and compares string to string for user authentication.
Analysis
Reflect upon your results of the measurement to ascertain your achievement of the particular course objective.
- How did you do?
- i did well but could learn a great deal more
- Is there room for improvement?
- yes
- Could the measurement process be enhanced to be more effective? Of course this is only mt perspective.
unix Keywords
■The UNIX Shell
■ Environment variable
■ Source Code, Object Code, Binary Code, Library……x
■ Source Code, Object Code, Binary Code, Library
■ Filtering
■ networking, UNIX Networking Tools
■ Security
■ X Window System
Filtering (Unix)
Definition
filtering is a way to process text in a usable manner for the goal that is in mind.
Demonstration
some filtering utilities
cat(1) - concatenate files cut(1) - cut text grep(1) - globally search for regular expression and print head(1) - print first “n” lines of output sed(1) - stream editor sort(1) - sort output tail(1) - print last “n” lines of output tr(1) - translate characters uniq(1) - filter out duplicate lines from sorted file wc(1) - word count
lab46:~$ cat sample.db name:sid:major:year:favorite candy* Jim Smith:105743:Economics:Sophomore:Lollipops* Adelle Wilson:594893:Sociology:Junior:Ju-Ju Fish* Sarah Billings:938389:Accounting:Freshman:Tic-Tacs* Eric Vincent:1001119:Biology:Freshman:Lollipops* Linus Torvalds:4432001:Computer Science:Senior:Snickers* Alan Cox:40049300:Computer Science:Senior:Whoppers* Alan Turing:40030333:Computer Science:Senior:Rock Candy* Eric Vincent:1001119:Biology:Freshman:Lollipops* John Doe:0000000:Unknown:Freshman:unknown* Leet Haxzor:31337:Business:Sophomore:Gobstoppers* Matthew Green:439478:Philosophy:Junior:Necco Wafers* Megan Tanner:372233:Physics:Junior:Zero Bar* Junior Mint:2228484:Liberal Arts:Junior:Junior Mints* Alan Wilson:22908948:Economics:Freshman:Whoppers* Kris Warner:8383833:Biology:Senior:Mars Bar* Jill Ashley:9939392:Chemistry:Freshman:Warheads* Francois Laroux:93938383:Anthropology:Sophomore:Bubblegum* lab46:~$ cat sample.db | grep Biology Eric Vincent:1001119:Biology:Freshman:Lollipops* Eric Vincent:1001119:Biology:Freshman:Lollipops* Kris Warner:8383833:Biology:Senior:Mars Bar* lab46:~$ cat sample.db | grep Biology | grep Lollipops Eric Vincent:1001119:Biology:Freshman:Lollipops* Eric Vincent:1001119:Biology:Freshman:Lollipops* lab46:~$ echo "hello there:this:is:a:bunch of:text." | cut -d":" -f1 hello there lab46:~$ echo "hello there:this:is:a:bunch of:text." | cut -d":" -f2 this lab46:~$ echo "hello there:this:is:a:bunch of:text." | cut -d":" -f3 is lab46:~$ echo "hello there:this:is:a:bunch of:text." | cut -d":" -f1,6 | sed -e 's/:/ /g' hello there text. lab46:~$ sort sample.db sorts alphabetically Adelle Wilson:594893:Sociology:Junior:Ju-Ju Fish* Alan Cox:40049300:Computer Science:Senior:Whoppers* Alan Turing:40030333:Computer Science:Senior:Rock Candy* Alan Wilson:22908948:Economics:Freshman:Whoppers* Eric Vincent:1001119:Biology:Freshman:Lollipops* Eric Vincent:1001119:Biology:Freshman:Lollipops* Francois Laroux:93938383:Anthropology:Sophomore:Bubblegum* Jill Ashley:9939392:Chemistry:Freshman:Warheads* Jim Smith:105743:Economics:Sophomore:Lollipops* John Doe:0000000:Unknown:Freshman:unknown* Junior Mint:2228484:Liberal Arts:Junior:Junior Mints* Kris Warner:8383833:Biology:Senior:Mars Bar* Leet Haxzor:31337:Business:Sophomore:Gobstoppers* Linus Torvalds:4432001:Computer Science:Senior:Snickers* Matthew Green:439478:Philosophy:Junior:Necco Wafers* Megan Tanner:372233:Physics:Junior:Zero Bar* Sarah Billings:938389:Accounting:Freshman:Tic-Tacs* name:sid:major:year:favorite candy* lab46:~$ head -5 sample.db "print first 5 lines" tail does opposite prints last -n lines of file specified name:sid:major:year:favorite candy* Jim Smith:105743:Economics:Sophomore:Lollipops* Adelle Wilson:594893:Sociology:Junior:Ju-Ju Fish* Sarah Billings:938389:Accounting:Freshman:Tic-Tacs* Eric Vincent:1001119:Biology:Freshman:Lollipops*
Security (UNIX)
Definition
Security is ability to allow and/or deny access to information that is vital to any multi-user system.
Demonstration
To be able to change permissions, allow access for new directories created along with new files is just some of the basic but must be taken into account. below is a command line which will display the umask
lab46:~$ umask 0022 lab46:~$ touch newfile lab46:~$ ls -l newfile -rw-r--r-- 1 rmatsch lab46 0 Apr 21 12:18 newfile lab46:~$
This means your default umask is set to this meaning that any files you make will have this minused the full permissions so a normal file full permission would be 666 but now when a new file is created thanks to umask the permissions on the file in octal are 644 which mean the owner can read and write to the file and everyone else can only read and same for group.
lab46:~$ mkdir newdirect lab46:~$ ls -ld newdirect drwxr-xr-x 2 rmatsch lab46 6 Apr 21 12:19 newdirect
full permission on a directory is 777 so 777 -22 = 755 which is show above with the owner having read write execute and group and world having only read and execute privileges.so umask is a very important thing to know if you are considering security of the system and users.
When you don't have access:
lab46:~$ cd /root -bash: cd: /root: Permission denied lab46:~$ chmod 077 newdirect "change newdirect's permissions to 077" lab46:~$ cd newdirect -bash: cd: newdirect: Permission denied
The unix shell (unix)
Definition
The Unix shell is a command-line interpreter that provides a user interface for Unix/linus operating systems. Users directly operate with the computer by entering commands execute, create, delete, and various other operation. There is no “ button clicking like windows computers”
Demonstration
At a command line interpreter such as bash or various other you can search through files, list files,create new files, copy files, delete files, make directories, and so on.Below is a demonstration of the various nothing i talked about just showing you that all task or “moving around the sytem is done through commands.
lab46:~$ ls 2 badname.tgz newdirect CCC.sh bin phenny CCCclasses.sh class_notes phenny.tar.bz2 Desktop classlog.c regex.html Documents count.c sample.db Downloads data spring2010-20091022.html Maildir fall2010-20100315.html spring2010-20101113.html Music fall2010-20101113.html spring2011-20101105.html Pictures fall2011-20110417.html spring2011-20101113.html Public file spring2012-20111103.html Templates index.html src Videos lab1 stdout archives labD.sh winter2011-20101113.html badname motd lab46:~$ cp count.c count.xxxxxxxxxxxxxx lab46:~$ rm count.c rm: remove regular file `count.c'? y lab46:~$ mkdir newdirect2 lab46:~$ touch newfile lab46:~$ ls 2 bin newfile CCC.sh class_notes phenny CCCclasses.sh classlog.c phenny.tar.bz2 Desktop count.xxxxxxxxxxxxxx regex.html Documents data sample.db Downloads fall2010-20100315.html spring2010-20091022.html Maildir fall2010-20101113.html spring2010-20101113.html Music fall2011-20110417.html spring2011-20101105.html Pictures file spring2011-20101113.html Public index.html spring2012-20111103.html Templates lab1 src Videos labD.sh stdout archives motd winter2011-20101113.html badname newdirect badname.tgz newdirect2 lab46:~$ grep hey regex.html <td NOSAVE><b><u><font size=+1>Objective:</font></u></b> To become familiar with the UNIX command line through exposure to some simple commands. The student will also be presented with traditional UNIX conventions they are expected to become familiar with and use throughout the semester.</td> How have they changed?</td> lab46:~$ cd .. lab46:/home$ ls bherrin2 dh018304 hshaikh jsmit176 mdecker3 rmatsch tp001498 bhuffner dherman3 hwarren1 jstrong4 mdittler rmoses triley2 bkenne11 dlalond1 ian jsulli34 mearley1 rnewman ts004985 bobpauljr dmay5 javery9 jtongue2 mgough rpetzke1 wedge bort dmckinn2 jbaez jtreacy mguthri2 rraplee wezlbot bowlett1 dmurph14 jbamper jtripp mhenry9 rrichar8 wfischba brian dpadget8 jbarne13 jv001406 mkellogg rsantia4 wknowle1 brobbin4 dparson3 jbesecke jvanott1 mkelsey1 rshaw8 wroos bstoll dpotter8 jblaha jwalrat2 mmatt rthatch2 ystebbin btaber2 dprutsm2 jblanch1 jwhitak3 mowens3 ryoung12 zlittle bwheat drobie2 jbrant jwilli30 mp018526 sblake3 zmccann bwilso23 ds000461 jbrizzee jwilso39 mpage9 sc000826 zward lab46:/home$ cd rmatsch lab46:~$ cd src lab46:~/src$ ls Makefile cprog hello1 hello1.c helloC helloC.c submit unix lab46:~/src$ cd unix lab46:~/src/unix$ ls arc.tar.gz cs4.txt cs9.txt lab0.txt lab5.txt laba.txt contact.info cs5.txt csA.txt lab1.txt lab6.txt link.sh cs1.txt cs6.txt csB.txt lab2.txt lab8.txt scripting cs2.txt cs7.txt csC.txt lab3.txt lab9.txt shell cs3.txt cs8.txt devel lab4.txt labC.txt unix_html_stuff lab46:~/src/unix$
Environment Variables
Definition
environment variables are significant and can be thought of in a sense to create the operating environment in which a process runs. environment variables set at login are valid for the duration of the session. Environment variables have UPPER CASE as opposed to lower case which are shell variables.
Demonstration
USER (your login name) HOME (the path name of your home directory) HOST (the name of the computer you are using) ARCH (the architecture of the computers processor) DISPLAY (the name of the computer screen to display X windows) PRINTER (the default printer to send print jobs) PATH (the directories the shell should search to find a command)
lab46:~$ echo $HOME /home/rmatsch lab46:~$ echo $PATH /home/rmatsch/bin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games lab46:~$ echo $OSTYPE linux-gnu lab46:~$ echo $USER rmatsch lab46:~$ echo $home lab46:~$
X window system
Definition
a software system which provides a basis for GUI's and has good input device capability for computers. basically it is used to build graphical user interfaces for unix like operating systems originally designed for network connection.
unix networking tools
Definition
tools used to gain networking information such as the host you are connected to and various other network data that may be useful.
Demonstration
some of the two most important networking tools i think are netstat, ping below are example of them to find information on dns server to see if packets or being sent and network information.
lab46:~$ ping localhost PING localhost.localdomain (127.0.0.1) 56(84) bytes of data. 64 bytes from localhost.localdomain (127.0.0.1): icmp_req=1 ttl=64 time=0.045 ms 64 bytes from localhost.localdomain (127.0.0.1): icmp_req=2 ttl=64 time=0.037 ms 64 bytes from localhost.localdomain (127.0.0.1): icmp_req=3 ttl=64 time=0.038 ms 64 bytes from localhost.localdomain (127.0.0.1): icmp_req=4 ttl=64 time=0.036 ms ^C --- localhost.localdomain ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 2997ms rtt min/avg/max/mdev = 0.036/0.039/0.045/0.003 ms netstat Active Internet connections (w/o servers) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 lab46.offbyone.la:60002 irc.offbyone.lan:ircd ESTABLISHED tcp 0 0 lab46.offbyone.lan:ssh mobile-198-228-20:58895 ESTABLISHED tcp 0 0 lab46.offbyone.la:47089 irc.offbyone.lan:ircd ESTABLISHED lab46:~$ netstat -ta Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 *:ssh *:* LISTEN tcp 0 0 *:35801 *:* LISTEN tcp 0 0 *:nfs *:* LISTEN tcp 0 0 *:3939 *:* LISTEN tcp 0 0 *:3333 *:* LISTEN tcp 0 0 lab46.offbyone.lan:5000 *:* LISTEN tcp 0 0 lab46.offbyone.lan:5007 *:* LISTEN tcp 0 0 *:59343 *:* LISTEN tcp 0 0 *:sunrpc *:* LISTEN tcp 0 0 *:csync2 *:* LISTEN tcp 0 0 lab46.offbyone.lan:4242 *:* LISTEN tcp 0 0 lab46.offbyone.la:60002 irc.offbyone.lan:ircd ESTABLISHED tcp 0 0 lab46.offbyone.lan:ssh mobile-198-228-20:58895 ESTABLISHED tcp 0 0 lab46.offbyone.la:47089 irc.offbyone.lan:ircd ESTABLISHED tcp 0 0 lab46.offbyone.la:47998 irc.offbyone.lan:ircd ESTABLISHED tcp 0 0 lab46.offbyone.la:42140 auth1.offbyone.lan:ldap ESTABLISHED tcp 0 0 lab46.offbyone.la:45645 irc.offbyone.lan:ircd ESTABLISHED tcp 0 0 lab46.offbyone.la:58347 vm31.student.lab:ssh ESTABLISHED tcp 0 0 lab46.offbyone.la:44392 irc.offbyone.lan:ircd ESTABLISHED tcp 0 0 lab46.offbyone.la:51839 auth1.offbyone.lan:ldap ESTABLISHED tcp 0 0 lab46.offbyone.la:47426 irc.offbyone.lan:ircd ESTABLISHED tcp 0 0 lab46.offbyone.la:33595 auth1.offbyone.lan:ldap ESTABLISHED tcp 0 0 lab46.offbyone.la:44549 irc.offbyone.lan:ircd ESTABLISHED netstat -s |less Ip: 44800188 total packets received 2 with invalid addresses 280120 forwarded 0 incoming packets discarded 44488743 incoming packets delivered 58096734 requests sent out 7068 outgoing packets dropped Icmp: 10051 ICMP messages received 28 input ICMP message failed. ICMP input histogram: destination unreachable: 9389 echo requests: 250 echo replies: 412 9622 ICMP messages sent 0 ICMP messages failed ICMP output histogram: destination unreachable: 659 redirect: 7068 echo request: 1645 echo replies: 250 IcmpMsg: InType0: 412 InType3: 9389 InType8: 250 OutType0: 250 OutType3: 659 OutType5: 7068 OutType8: 1645 Tcp: 80063 active connections openings 38145 passive connection openings 26780 failed connection attempts 4252 connection resets received 85 connections established 44040550 segments received 57184990 segments send out 96026 segments retransmited 0 bad segments received. 30648 resets sent Udp: 388512 packets received
Compiler, Assembler, Linker, Loader
Definition
Demonstration
Demonstration of the chosen keyword.
If you wish to aid your definition with a code sample, you can do so by using a wiki code block, an example follows:
/* * Sample code block */ #include <stdio.h> int main() { return(0); }
Alternatively (or additionally), if you want to demonstrate something on the command-line, you can do so as follows:
lab46:~$ cd src lab46:~/src$ gcc -o hello hello.c lab46:~/src$ ./hello Hello, World! lab46:~/src$
Source Code, Object Code, Binary Code, Library
Definition
source code is code written by a programmer in a text editor, object code is the source code compiled and ready to be linked to the binary code which is the binary executable the processor reads. library can be thought of as a place where header files are located.
Demonstration
lab46:~$ vi hello.c lab46:~$ file hello.c hello.c: ASCII C program text lab46:~$ gcc -c hello.c lab46:~$ ls hello.c hello.o lab46:~$ file hello.o hello.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped lab46:~$ gcc -o helo hello.o lab46:~$ file helo helo: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, not stripped lab46:~$ file hello.o hello.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped lab46:~$ file hello.c hello.c: ASCII C program text
unix Objective
unix Objective
students should be able to set permissions on file directories ad be able to filter text using utilities
Definition
the objective entails using reg expression cut(1),tr(1), and many more tools to filter text and be familiar with unix security.
Method
Tell students to find what the default file and directory access is set to and how to change that default permission using umask and have an understanding of what is happening. ask students to search through a document and put the information into a useable manner by filtering the document or database. students should also be asked to change the permissions using chmod utility and demonstrate a clear understanding in permissions and security
Measurement
lab46:~$ umask 0022 lab46:~$ touch file lab46:~$ ls -l file -rwxr-xr-x 1 rmatsch lab46 7481 Apr 21 16:21 file lab46:~$ umask 000 lab46:~$ touch file2 lab46:~$ ls -l file2 -rw-rw-rw- 1 rmatsch lab46 0 Apr 21 16:21 file2 lab46:~$ umask 22 lab46:~$ mkdir newd lab46:~$ ls -ld drwx-----x 30 rmatsch lab46 4096 Apr 21 16:23 . lab46:~$ ls -ld newd drwxr-xr-x 2 rmatsch lab46 6 Apr 21 16:23 newd lab46:~$ umask 22 lab46:~$ chmd -bash: chmd: command not found lab46:~$ chmod 777 newd lab46:~$ ls -ld newd drwxrwxrwx 2 rmatsch lab46 6 Apr 21 16:23 newd lab46:~$
1 is execute read is 4 and write is 2
Analysis
Reflect upon your results of the measurement to ascertain your achievement of the particular course objective.
- How did you do?very good
- Is there room for improvement?yes
- Could the measurement process be enhanced to be more effective?yes
- Do you think this enhancement would be efficient to employ?yes
- Could the course objective be altered to be more applicable? How would you alter it?no
Experiments
Experiment 7
Question
what will happen if you remove #ndef #define #endif from header files and re compile
Resources
Class notes
Hypothesis
I think the program will compile with out any problems.
Experiment
take a c++ program with multiple header files and remove the #ndef statements and see what happens.
Data
it compiled with out the statements.
Analysis,Conclusion
Based on the data collected:
- Was your hypothesis correct? yes my hypothesis was correct and i was able to compile.
- Was your hypothesis not applicable?yes
upon further investigation in small problems probably wont matter so much but with many header files and larger programs this could be a big plus to have.
Experiment 8
Question
can kids touch there parents private parts (C++ inheritance)
Resources
Mathew hass
Hypothesis
no kids to parent relationships cannot touch there parents private parts because then it would not be a private class if the kid had a friend and then third parties could touch the parents private parts which is not good for security.
Experiment
develop a program and set certain variables to private class and then try to access these variables via a kid of the parent.
Analysis
Based on the data collected:
- Was your hypothesis correct?yes
- Was your hypothesis not applicable?yes
- Is there more going on than you originally thought? yes(shortcomings in hypothesis)
- What shortcomings might there be in your experiment? taking into account friends
Conclusions
C++ is great for code management and for security purposes as data access..
Retest 3
State Experiment
josh Davis experiment “IF or not if” http://lab46.corning-cc.edu/opus/spring2012/jdavis34/start#experiment_if_or_not_if
Resources
Evaluate their resources and commentary. Answer the following questions:
- Do you feel the given resources are adequate in providing sufficient background information?
- Are there additional resources you've found that you can add to the resources list?
- Does the original experimenter appear to have obtained a necessary fundamental understanding of the concepts leading up to their stated experiment?
- If you find a deviation in opinion, state why you think this might exist.
Hypothesis
What is the use of \n and to what effect does it have if in a simple program designed to print “hello world” if: 1. it exists.
2. it does not I feel their hypothesis is adequate in capturing the essence of what they're trying to discover. and there is no adjustments i would make.
Experiment
Follow the steps given to recreate the original experiment. Answer the following questions:
- Are the instructions correct in successfully achieving the results?
there is not to many directions to establish how to do it if i did not have any knowledge of C I feel there room for improvement in the experiment instructions/description such as a small snip of code.
- Would you make any alterations to the structure of the experiment to yield better results?
no it is a simple experiment so there structure would do.
Data
#include <stdio.h>
int main()
{
printf("hello, world\n");
printf("hello,\n world");
return(0);
}
lab46:~$ gcc -o hello hello.c lab46:~$ ./hello hello, world hello, world
Analysis
Answer the following:
- Does the data seem in-line with the published data from the original author?
Yes the data seems in-line with the author
- Can you explain any deviations?
There is no deviations.
- Is the stated hypothesis adequate?
Yes the stated hypothesis is adequate.
Conclusions
Answer the following:
- What conclusions can you make based on performing the experiment?
\n will make a new line
- Do you feel the experiment was adequate in obtaining a further understanding of a concept? yes
- Does the original author appear to have gotten some value out of performing the experiment?yes
Good job experiment was done well.
